Again, .onErrorReturnItem() is a lot like .onErrorReturn() but is even simpler. In this case, it just returns a constant that was specified at the time an Observable was created, as here:

Observable.<String>error(new Error("Crash!"))
        .onErrorReturnItem("ReturnItem")
        .subscribe(item -> {
            log("subscribe", item);
        }, e -> log("subscribe", e));